Subjectively, that's my experience too.

I believe, but I'm not certain, that it is possible to have a 'good' amplifier in  which the global negative feedback can be varied by means of a potentiometer. As the feedback is increased, the distortion is reduced and, presumably, the 'null test' response improves.

The question is, where would we adjust the global feedback pot to if we're tuning by ear for maximum 'realism'.

We really need Thorsten or someone who could knock up such a contraption.

Regarding speakers, there is a school which goes for quite resonant enclosures with minimum damping (padding and stuffing), à la AudioNote, for a more musical overall sound. I believe in the philosophy of minimum damping for the same reason but attempt to design less resonant enclosures. Chaque à son gout (or something - Chirac's in town).